Heidelberg 2006 – scientific programme

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UP: Umweltphysik

UP 15: Poster: Atmosph
äre und Klima

UP 15.2: Poster

Tuesday, March 14, 2006, 14:00–16:00, C

Retrieval of tropospheric NO₂ by synergistic use of ENVISAT/SCIAMACHY and ground-based solar FTIR measurements at the Zugspitze — •Ralf Sussmann¹, Wolfgang Stremme¹, Johan P. Burrows², Andreas Richter², Wolfgang Seiler¹, and Markus Rettinger¹ — ¹Forschungszentrum Karlsruhe, IMK-IFU, Garmisch-Partenkirchen — ²Universität Bremen, Institut für Umweltphysik

Columnar NO₂ from FTIR measurements at the Zugspitze (47^∘ N, 11^∘ E, 2964 m asl.) was investigated synergistically with SCIAMACHY satellite data (Univ. Bremen algorithm UB1.5). A new concept to match FTIR data to the time of satellite overpass makes use of the NO₂ daytime increasing rate retrieved from the FTIR data set. SCIAMACHY data within a 200-km selection radius were considered, and a pollution-clearing scheme was developed to select only pixels corresponding to clean background tropospheric conditions. Analysis of the averaging kernels gives proof that at mountain-site FTIR is a highly accurate measure for the stratospheric column, while SCIAMACHY shows significant tropospheric sensitivity. Based on this finding, we set up a combined a posteriori FTIR-SCIAMACHY retrieval for free tropospheric NO₂. It yields an annual cycle with variations between 0.75-1.54E+15 cm⁻² and an intermediate phase between that of the well known boundary layer and the stratospheric annual cycles. The outcome is a concept for an integrated global observing system for tropospheric NO₂ that comprises DOAS NADIR satellite measurements and a set of latitudinally distributed mountain-site or clean-air FTIR stations.